Walking Off a Moon

One of the challenges of any space mission is getting into orbit.  While writing the entry "Mining the Moons of Mars" an idea emerged that has some interesting academic potential.  One of the "non-traditional" suggestions for placing objects in orbit is to construct a space tower, although most sci-fi series prefer using a space elevator, by creating a tall enough structure a civilization can avoid much of the energy expenditure required of more traditional rocket launches.  For the planet Earth building such a structure would require tremendous advances in science and engineering, a space tower on a Martian moon is a far more straightforward affair.  

Imagine for a moment that for some small rocky bodies in our solar system the song "Stairway to Heaven" isn't just some song that everyone who picks up a guitar has the urge to play.  Under the right circumstances a small body with enough rotation could be altered to allow for the construction of a series of stairs or a ramp that would allow denizens of a planet to walk up into orbit around there world.

Phobos has the most data on its Wikipedia entry and as such will be the source of the general calculations.  

(For reference I am using the equation found here and relevant data from the Phobos Wikipedia entry)  

r is the unknown variable being solved
G is the Gravitational Constant =6.67428e-11 m^3/kg*s^2M represents Mass of Phobos=1.072e16 kg 

ω is the angular velocity of Phobos along its equator and will need to be solved for.
To do this the length of a Phobian day must be estimated.  (As Phobos isn't a proper sphere some liberties have been taken.)
Mean Radius of Phobos=11.1 km =Rmean

Equatorial Rotational Velocity=11km/hr=V
Length of Day=Rmean*π*2/V

Phobian "Day" 6.34 hrs 

From the length of the Phobian day we can then calculate the angular velocity
ω=[2*π*radians]/[6.34hrs*3600(s/hr)]= 2.75*e-4 radians/second

Now for the epic plug and chug

r=[{(6.67428e-11 m^3/kg*s^2)*(1.072e16 kg)}/{(2.75e-4rad/s)^2}]^(1/3)
unit reduction (radians are unit-less and are being dropped)
r=[{7.15482816e5 m^3}/{7.5625e-8}]^(1/3)
MOAR REDUCTIONS!!
r=[9.4609298e12 m^3]^(1/3)=[9.4609298e12]^(1/3) meters

r=21,135 meters or 21.135 km from the center of Phobos

From all that it was calculated that Phobosynchroneous orbit should be achieved 21.135 km from the
center of Phobos, or roughly a little over 10 km from the average surface altitude.  As a point of reference 
the tallest man made tower on Earth is the Burj Khalifa at 829.8 meters, a little less than 1/12 the height
of this sci-fi structure.  Now here's the fun bit, the force of gravity on Phobos is 1166 times weaker than
on the Earth's surface, drastically reducing the challenge of building this tower.  What is even cooler, but
much harder to solve for (read I'm still looking in to how to do the math), is that the tower components 
would weigh less at higher parts of the tower.  I will try to follow up with some basic tower design
approaches.

The potential practical applications for building a space elevator on a small moon deal mostly with

fuel delivery and development of space craft construction.  As mentioned in previous entries and on the
linked Wikipedia articles, there is a distinct possibility for finding large deposits of water on Phobos, 
providing the fuel delivery argument.  As to space craft, that is further off, consider the ability to have a 
construction platform that is within a few miles of its source materials, impossibly close by interplanetary
standards, but is still capable of building in a micro-gravity environment.  That is the potential of a tower
on Phobos.  The coolest part, would be the ability to climb a 6 mile tall building and step off into the
expanse of space.

Editorial Note (April 24) After getting some notes from my friend Andrew Tremblay, I have made some
mild revisions.

Follow Up 10/1/2015  A cool suggestion from NASA to look into landing on Phobos before a fully
 fledged Mars mission, while the ramp makes little sense, building a small scale space elevator, or ideally
 a series of elevators around Phobos would allow future mission planners extremely high flexibility on
future missions.

Hyper Rugged Cameras

One of my personal favorite consumer electronics genres has to be the rugged digital camera, when you're dragging yourself through mud, diving on a remote coral reef, what have you, this technology means you can cost effectively record your memories, totally awesome.  What is slightly less awesome is that the current approach to the ruggedized cameras doesn't go far enough to make them life proof.  The need to have access to the camera's battery and memory modules makes it necessary to rely on some type of ruggedized gasket to, hopefully, keep the elements at bay, a rather large point of potential failure.  In the era of incredibly cheap memory and wireless data modules combined with the adoption of inductive charging for home electronics we have a solution for a stronger camera.

Instead of selling a camera to home consumers where they must supply the memory card, why not have the camera have the memory capacity embedded, general consumers can already buy flash memory at well under $1/GB of storage capacity electronics manufacturers can comfortably add a large memory system to a mid-level compact camera without harming the bottom line too much.  Additionally when you look at developments to create smarter point and shoot platforms whereby photos can automatically be uploaded not only by WiFi but over cellular networks, it is surprising to see that integrated camera memory isn't exploited more.

The battery question is a little fuzzier depending on how a business wants to treat its target markets.  From the perspective of creating a rugged compact camera, having a removable battery causes more problems than it solves.  As mentioned earlier the ability to remove the battery pack requires an opening within the case of the camera that increases the likely-hood of moisture and dust coming into contact with more sensitive components.  Instead of a removable battery design the camera to have a built in inductive charging module, with wireless charging there is no need for the case of the camera to have any openings.  To allay consumer concerns about their inability to change batteries mid trip, product developers could compensate in a range of ways, making the camera as energy efficient as possible (this would minimize hardware costs over larger production runs), expanding the battery system to take advantage of the volume that would have been needed for housing a removable battery system, and finally (at least as far as I can think of) having some kind of solar/battery operated inductive charger unit sold separately (device manufacturers love this kind of thing anyways).  

Wise Welding Warriors

As rapid prototyping technology has become more popular and affordable over the last decade, there has been a range of chatter and in some cases experimentation with integrating rapid prototyping technology into front line applications.   Think tanks associated with the Department of the Navy have put forth more long term suggestions, including the development of autonomous manufacturing facilities capable of filtering source materials for manufacturing war material from sea water.  On a more practical front the US Army is already beginning to test small scale platforms intended to operate at Forward Operating Bases (FOBs) in Afghanistan. These shipping container sized facilities, called Expeditionary Lab Mobile (ELM), house a range of tools for creating solutions to problems encountered by airmen/marines/sailors/soldiers serving on the front lines and are budgeted to operate with trained engineers who will design and fabricate what ever is needed.
While I am a huge fan of rapid prototyping technologies, I think that the Army's current approach to front line manufacturing facilities doesn't go far enough for the war-fighter.  It is one thing to shorten the development cycle for new tools for the front line, it is another thing entirely to have servicemen and women be the individuals developing that new technology.
In countless commercials recruiting for the US Armed forces the audience is told that the skills they gain while serving their country overseas.  With developments like the ELM the Department of Defense has a unique opportunity to provide our war-fighters with an invaluable skill that will last a life time.  In addition to having professional engineers on staff the armed forces should work to provide direct access to those serving.  War-fighters could be trained in the use of the entire fabrication facilities tools, with a certification program that would have published standards so that civilian employers would have a clear understanding of what skills had been gained during an individuals service.  Ideally the certification program would emphasize flexibility, any serviceman or woman would have the option of learning how to use the tools of the fabrication facilities, either while deployed or while working on base.  To promote participation in the Fab-Lab certification program the Department of Defense could sponsor a myriad of design competitions, and for challenges encountered on the front lines.   Officers serving combat duties should also be able to provide a cash bounty for the most effective solutions to their particular needs (preferably the creators of design solutions would receive both monetary compensation and active recognition by their command superiors) .
There is no guarantee that such a program would be perfect, but if the maker movement is any indication, the more talent we unleash to solve problems the better future we can create.

Mining the Moons of Mars

In previous posts I have talked about the resource potential of mining the Earth's moon for resources that would be incredibly useful for larger scale exploration of our solar system.  While the lunar surface has a ready abundance of oxygen in its regolith the availability of elements like hydrogen is far less impressive generally less than .1% of lunar regolith containing water.  While a range of project proposals have been put forth as to how we might still produce water on the moon, including simply shipping hydrogen from the Earth,  few publicly available papers discuss utilizing a multi-celestial body resource exchange.  The papers that do generally concern themselves with mining resources on the Martian surface.  If the intent of your program is to send a return mission from the Martian surface, by all means establishing some kind of Martian fuel refinery makes sense.  

        

If you simply want components for rocket fuel there is no need to land on the surface.  The moons of Mars, Deimos and Phobos, have tremendous potential for resource mining.  Two key properties make them extremely attractive for export oriented mining operations soil and gravity.  The soil composition of both moons include Carbonaceous chondrites (a category of minerals that can be rich in compounds like water and amino-acids).  The availability of carbonaceous chondrites alone would not make the Martian moons more appealing than their parent world as Mars has a range of potential compounds that could serve just as well as rocket fuel source materials, this is where the pull of gravity becomes a major factor.  Escaping the bonds of the Earth requires a space craft achieve a speed of 11.2 km/s (about 45X faster than a passenger jet plane's cruising speed) on Mars a spacecraft would need to achieve a speed of 5km/s.  For an explorer on the surface of Deimos launching into orbit would simply require that they be able to run at speeds over 20km/h (roughly 13 mph) on Phobos only Olympic athletes would be able to achieve escape velocity on foot (40km/h), so long as the spacesuit didn't interfere too much with their running technique (I'm ignoring any clever use of taking advantage of rotation).  

A mining operation working on the Martian moons would be able to launch materials into orbit with a standard baseball pitching machine (so long as they were only sending up small volumes).  Moving the material from orbits of the moons to locations that would be useful for spacecraft, refining facilities, construction platforms, etc...would still require a certain degree of fuel and that fact should not be ignored.  

If the resources found on Phobos and Deimos a viable quantity of high water content minerals, there would be relatively little need for a complex inter planet exchange of resources, water could "simply" be extracted from the rock and used as needed, spacecraft refueling upon arrival in Martian orbit.  That being said it would not be unreasonable to form a trade network between the Earth, its moon, and the moons of Mars, to provide a range of resources.  The Earth providing complex components, the moon generally providing oxygen, and Phobos and Deimos supplying organic compounds.  At this time there is no guarantee that we possess the necessary technologies to make this idea financially viable, but as more firms enter the fray to make a profit in our final frontier it is important to enter a point of paradigm blindness, where only free floating asteroids or the Lunar surface are considered for establishing humanities foothold among the stars.

Update July 8 2013, so it turns out that this idea was proposed at least as early as 1985 with the title 

"Phobos and Deimos (PhD): Concept for an Early Human Mission for Resources and Science" on the upside it turns out this idea warranted a PhD, so that's cool.